By Gabriel Stargardter and Gustavo Palencia
TEGUCIGALPA (Reuters) - Four days after voting in a presidential election, Honduras sank deeper into crisis on Thursday, with no clear winner in sight and the vote count disputed by the U.S.-friendly incumbent's centrist rival, a television game show host allied with leftists.
Both President Juan Orlando Hernandez and his TV star challenger, Salvador Nasralla, claimed victory after Sunday's election, which first favored the opposition candidate but then swung towards the incumbent after a hold-up in the count.
International concern has mounted over a growing political crisis in the Central American nation, battling poverty, drug gangs and one of the world's highest murder rates.
On Wednesday, the U.S. State Department urged a quick conclusion to the vote count in Honduras, one of Washington's closest military and ideological allies in the region.
The Organization of American States (OAS) appeared to have salvaged the credibility of the election on Wednesday by eliciting signed statements from both candidates vowing to respect the final result once disputed votes had been checked.
A few hours later, however, Nasralla, who initially held a five-point lead, rejected the OAS accord he had signed, saying his opponents were trying to rob him, and urged supporters to take to the streets of the capital Tegucigalpa to defend his triumph.
Later on Wednesday, police fired tear gas to disperse Nasralla supporters gathered outside the election tribunal where the vote was being counted. The fumes entered the building, prompting its staff to be evacuated, television images showed.
On Monday, the tribunal published more than half of the results, but faced criticism for a subsequent 36-hour delay releasing further results.
When the count started again, Hernandez began to reel in Nasralla. With 82.89 percent of ballots counted, the center-right Hernandez had secured 42.2 percent of the vote, while Nasralla was on 42.1 percent, the tribunal said.
The count halted again late on Wednesday afternoon, and the tribunal blamed the delay on computer glitches.
"They take us for idiots and want to steal our victory," said Nasralla, who heads a left-right coalition. "The document I signed today with the OAS has no validity."
The OAS expressed its regret at Nasralla's withdrawal from the agreement and vowed to keep working for a just result.
International observers said the delays were damaging the credibility of authorities, and risked undermining the winner's legitimacy.
Ahead of the election, opinion polls indicated that Hernandez was favorite to win the vote in the poor Central American country of more than 9 million people.
Nasralla is one of Honduras' best-known faces and is backed by former President Manuel Zelaya, a leftist ousted in a coup in 2009 after he proposed a referendum on his re-election.
(Editing by Dave Graham & Simon Cameron-Moore)